import * as Y from 'yjs';

import { NATIVE_UNIQ_IDENTIFIER } from '../consts.js';

export type OnBoxedChange = (data: unknown, isLocal: boolean) => void;

/**
 * Boxed is to store raw data in Yjs.
 * By default, store will try to convert a object to a Y.Map.
 * If you want to store a raw object for you want to manipulate the Y.Map directly, you can use Boxed.
 *
 * > [!NOTE]
 * > Please notice that the data will be stored in Y.Map anyway so it can not hold data structure like function.
 *
 * @example
 * ```ts
 * const boxedObject = new Boxed({ a: 1, b: 2 });
 * const boxedYMap = new Boxed(new Y.Map());
 * boxedObject.getValue().a; // 1
 * boxedYMap.getValue().set('a', 1);
 * boxedObject.setValue({ foo: 'bar' });
 * ```
 *
 * @typeParam T - The type of the value stored in the Boxed.
 *
 * @category Reactive
 */
export class Boxed<Value = unknown> {
  /**
   * Create a Boxed from a Y.Map.
   * It is useful when you sync a Y.Map from remote.
   *
   * @typeParam Value - The type of the value.
   *
   * @example
   * ```ts
   * const doc1 = new Y.Doc();
   * const doc2 = new Y.Doc();
   * keepSynced(doc1, doc2);
   *
   * const data1 = doc1.getMap('data');
   * const boxed1 = new Boxed({ a: 1, b: 2 });
   * data1.set('boxed', boxed1.yMap);
   *
   * const data2 = doc2.getMap('data');
   * const boxed2 = Boxed.from<{ a: number; b: number }>(data2.get('boxed'));
   * ```
   */
  static from = <Value>(
    map: Y.Map<unknown>,
    /** @internal */
    onChange?: OnBoxedChange
  ): Boxed<Value> => {
    const boxed = new Boxed<Value>(map.get('value') as Value);
    if (onChange) {
      boxed.bind(onChange);
    }
    return boxed;
  };

  /**
   * Check if a value is a Boxed.
   *
   * @example
   * ```ts
   * const doc = new Y.Doc();
   *
   * const data = doc.getMap('data');
   * const boxed = new Boxed({ a: 1, b: 2 });
   * Boxed.is(boxed); // true
   *
   * data.set('boxed', boxed.yMap);
   * Boxed.is(data.get('boxed)); // true
   * ```
   */
  static is = (value: unknown): value is Boxed => {
    return (
      value instanceof Y.Map && value.get('type') === NATIVE_UNIQ_IDENTIFIER
    );
  };

  private readonly _map: Y.Map<Value>;

  private _onChange?: OnBoxedChange;

  /**
   * Get the current value of the Boxed.
   */
  getValue = () => {
    return this._map.get('value');
  };

  /**
   * Replace the current value of the Boxed.
   *
   * @param value - The new value to set.
   */
  setValue = (value: Value) => {
    return this._map.set('value', value);
  };

  /** @internal */
  get yMap() {
    return this._map;
  }

  constructor(value: Value) {
    if (
      value instanceof Y.Map &&
      value.doc &&
      value.get('type') === NATIVE_UNIQ_IDENTIFIER
    ) {
      this._map = value;
    } else {
      this._map = new Y.Map();
      this._map.set('type', NATIVE_UNIQ_IDENTIFIER as Value);
      this._map.set('value', value);
    }
    this._map.observeDeep(events => {
      events.forEach(event => {
        const isLocal =
          !event.transaction.origin ||
          !this._map.doc ||
          event.transaction.origin instanceof Y.UndoManager ||
          event.transaction.origin.proxy
            ? true
            : event.transaction.origin === this._map.doc.clientID;
        this._onChange?.(this.getValue(), isLocal);
      });
    });
  }

  /** @internal */
  bind(onChange: OnBoxedChange) {
    this._onChange = onChange;
  }
}